This invention relates to a motor vehicle lift.
Motor vehicle lifts are known. They are constructed in the most various forms and sized according to their application and operator requirements, with obviously different performance and costs.
A known vehicle lifting device is the so-called "two column lift". It comprises a pair of vertical columns provided with a base for fixing to the floor and/or with members for connecting them together, and a pair of horizontal raisable arms. The two columns are generally positioned at a distance apart which exceed the maximum width of the vehicles to be lifted, and have their arms hinged to pivots parallel to the column axis. Rubber pads or other conventional members are provided at the opposite end of each arm to lift the vehicle to the required height as a result of the simultaneous raising of the two pairs of arms.
This type of vehicle lifting device is widely used, particularly in vehicle repair shops, as it combines substantially low cost with good operating reliability and the facility for lifting the vehicle to a height which enables the mechanic to work under it.
However, it also has serious limitations, and in particular:
large overall size, in that the two columns, their bases and the relative connections form a fixed installation which when not being used hinders proper vehicle handling within the workshop, whereas during periods of use it hinders the action of the mechanic, who for example can have difficulty in opening the door of the lifted vehicle,
the need for laborious installation in that the columns have to be fixed securely to the floor by fixing members expressly provided for this purpose,
considerable fatigue in carrying out the operations required for lifting the vehicle. In this respect, in order to be usable with vehicles of widely different widths the two columns must be sufficiently spaced apart to allow the widest vehicle to pass, whereas the arms must be of sufficient length to reach the narrowest vehicles. This large arm length means that when they are to be positioned under the body of a wide vehicle, it is very often necessary to carry out this operation in two stages by inserting one arm at a time and moving the vehicle along the ground forwards or backwards before inserting the second arm, to prevent it being hindered by the wheels.
So-called "parallelogram" lifts are also known, comprising a pair of longitudinal members resting on the ground, a pair of horizontal runways which can be raised relative to the longitudinal members to lift the vehicle disposed on them, and a number of pairs of arms or uprights hinged in the form of a parallelogram to the runways and longitudinal members, and operated by generally hydraulic systems to cause the runways to rise. This known type of lift is widely used, essentially because of its simplicity of installation, its strength and its reliability of operation. However it has limitations substantially in terms of its bulk and its difficulty of operation under certain conditions of use.
The bulk drawback also applies to its most favorable conditions, in that when the runways are raised, the longitudinal members, the uprights and the inevitable running boards or ramps for driving the vehicle onto the runways not only require a certain space, but represent and obstruction for the mechanics who have to work under the lifted vehicle.
Moreover, when the lift is raised, the fact that the vehicle rests on the runways by means of its wheels makes it impossible to do any work which requires the wheels to freely rotate or to be removed. For these reasons, it has previously been proposed to provide the runways with supplementary running boards which allow further lifting of the vehicle above the runways when the lift has already lifted the vehicle above the floor, but on the one hand this inevitably complicates the lift construction, and on the other hand it has not completely solved the problem in that the runways can obstruct access to the lower part of the vehicle in the region of the wheels.